Follow the Carbon — Carbon Capture Is Not the Destination

Carbon capture is becoming an increasingly important part of the climate and industrial-policy conversation. Capture rates. Tonnes captured. CO₂ pipelines. Storage hubs. Carbon utilisation. Carbon removals. These are all useful discussions. But there is a simple physical question that should come before almost all of them: What happens to the carbon after we capture it? Because capture itself is not a destination. It is a separation step. First, follow the carbon into the process Consider a conventional fossil-fuel system. The simplified carbon pathway is: geological carbon → extraction → fuel → conversion → CO₂ → atmosphere Carbon capture intervenes near the end of that chain. Instead of allowing all of the CO₂ to enter the atmosphere, part of it is separated from the exhaust or process stream. The pathway may then become: geological carbon → extraction → fuel → conversion → CO₂ → capture → ? That question mark matters. Until we know the next destination, we do not yet know the complete carbon outcome. Capture and storage One pathway is geological storage: CO₂ → conditioning → compression → transport → injection → geological formation Here the objective is to prevent captured carbon from entering the atmosphere by isolating it durably underground. The relevant system questions therefore extend beyond capture efficiency. How much CO₂ was actually captured? How much energy was required for capture, compression and transport? What emissions occurred elsewhere in the system? How much CO₂ reached the storage formation? How securely is it retained? How is the stored inventory measured and monitored? The Global CCS Institute reported 77 commercial CCS facilities operating globally and another 47 under construction as of July 2025, while the IEA’s March 2026 database tracks large-scale capture, transport, storage and utilisation projects worldwide. CCS is therefore moving increasingly from concept toward infrastructure. But infrastructure does not remove the need for carbon accounting. It makes accurate physical accounting even more important. Capture and utilisation Another pathway is: CO₂ → capture → conversion → product This is usually described as carbon capture and utilisation, or CCU. But “utilisation” covers very different carbon outcomes. Captured CO₂ might enter a material in which carbon remains bound for a long period. Or it might be converted into a fuel that is subsequently combusted, returning the carbon to the atmosphere. Both pathways use captured CO₂. They do not necessarily provide the same climate service. This is why the word utilised tells us less than it first appears. We have to keep following the carbon. If captured CO₂ becomes a fuel: Where does the carbon go when that fuel is used? If it becomes a material: How long does the carbon remain there? If it is subsequently recovered: Can it enter another useful cycle? The carbon molecule does not know whether we called the process “capture”, “utilisation” or “recycling”. It simply moves from one reservoir to another. Capture is not necessarily carbon removal This distinction is particularly important. Capturing CO₂ from a fossil-fuel process generally prevents some geological carbon from entering the atmosphere. That can substantially reduce emissions. But it is not physically identical to removing carbon that was already present in the atmosphere. Consider two pathways. Fossil carbon capture: geological reservoir → fuel → CO₂ → capture → geological storage Atmospheric carbon removal: atmosphere → capture or biological uptake → durable storage In the first case, the objective is largely to prevent a transfer. In the second, the objective is to reverse a previous transfer from the active carbon system. Both can matter. But they should not be counted or described as though they are the same physical process. The energy must also be followed Capturing carbon requires energy. So carbon analysis alone is insufficient. We must simultaneously ask: Where did the energy for capture come from? Capture systems may require heat, electricity, compression, pumping, refrigeration, regeneration of solvents or sorbents, and downstream CO₂ conditioning. That additional energy has its own physical origin. If supplying it creates additional emissions, those belong inside the system boundary. This does not make carbon capture inherently good or bad. It simply means the meaningful metric is not the gross amount of CO₂ entering the capture equipment. The meaningful result is the net carbon outcome across the complete system. Net zero, decarbonisation and defossilisation Carbon capture also demonstrates why these terms should not be used interchangeably. Net zero describes a balance between greenhouse-gas emissions and removals across a defined boundary. Decarbonisation reduces emissions or emissions intensity. Capturing and permanently storing fossil CO₂ can therefore be an important decarbonisation pathway, particularly for difficult industrial processes. Defossilisation asks a different upstream question: How much newly extracted geological carbon does the system continue to require? A process can become substantially decarbonised through capture while continuing to consume fossil carbon. That is not a contradiction. It simply means decarbonisation and defossilisation are measuring different changes in the physical system. Understanding that distinction can improve both policy and engineering decisions. Perhaps we need to measure carbon pathways, not just captured tonnes The global carbon-management sector is expanding. The IEA reports that more than 30 CCUS projects reached final investment decisions during the past two years and investment exceeded US$5 billion in 2025. Projects currently under construction could nearly double operational capture capacity by 2030. As that infrastructure develops, perhaps our language needs to become more precise too. A tonne of CO₂ captured is an important engineering measurement. But it is not yet the complete carbon story. We should also ask: Where did that carbon originate? How much was actually captured? What energy was required? Where was the carbon transported? Was it stored, converted, released or recirculated? How long did it remain outside the atmosphere? And did the pathway reduce the requirement to extract another unit of geological carbon? Carbon capture gives us control over a carbon stream. What we do with that control determines the outcome. So don’t stop at the capture plant. Follow the energy. Follow the carbon — all the way to its destination.